1. Field of the Invention
This invention relates generally to axisymmetric variable throat thrust vectoring nozzles and, more particularly, to a linear actuation and vectoring ring support and actuation apparatus for the actuating and supporting vectoring ring that is used to pivot the nozzle flaps that vector the nozzle exhaust flow.
2. Discussion of the Background Art
For military aircraft applications, there exists a need to increase the maneuverability of the aircraft, both for air to air combat missions and complicated ground attack missions. Aircraft designers seek to replace or augment the use of conventional aerodynamic surfaces such as flaps and ailerons with vectorable nozzles which turn or vector the exhaust flow and thrust of the gas turbine engine powering the aircraft. U.S. Pat. No. 4,994,660, issued to Hauer discloses an axisymmetric vectoring exhaust nozzle that provides a means for vectoring the thrust of an axisymmetric convergent/divergent nozzle by universally pivoting the divergent flaps of the nozzle in an asymmetric fashion or, in other words, pivoting the divergent flaps in radial and tangential directions with respect to the unvectored nozzle centerline. The flaps are pivoted by a vectoring ring which can be axially translated and gimballed or tilted about its horizontal and vertical axis (essentially have its attitude adjusted) through a limited range.
Vectored thrust produces tangential and radial loads referred to as side loads that are transmitted from the flaps by various load paths back to the engine casing through the actuators. These tremendous loads require heavy actuators to absorb the loads and, particularly, the bending moments exerted on the actuator shafts by thrust vectoring. U.S. Pat. No. 5,174,502, issued to Lippmeier et al. discloses a support for the vectoring ring that transfers at least a portion of the side loads acting generated by a gas turbine engine thrust vectoring nozzle to a relatively stationary portion of the engine. U.S. Pat. No. 5,174,502 discloses an apparatus to minimize or eliminate the side loads transferred by the nozzle to the actuators, reduce or eliminate the bending moments that the actuators would be subject to due to the radial loads, and to minimize the size and weight of the nozzle actuators and hydraulic system used to power the actuators. The support includes pivotal links that provides for allowing two degree of freedom (2 DOF) pivoting or gimballing motion and axial translation of the vectoring ring. One of the embodiments has a dual link support means with a rectangular first link pivotally attached to the engine casing by a hinge. The first link is pivotally connected to a second link which in turn is universally hinged to the vectoring ring by a 3 DOF or spherical joint.